For many diagnostic, therapeutic, or interventional percutaneous procedures involving the human vasculature, maintaining hemostasis is critical not only to prevent loss of blood, but also to prevent the introduction of air into the patient's vasculature system. Devices such as angioplasty balloon catheters, coronary guidewires, radio frequency (RF) ablation catheters, cryo-therapy catheters, and neurovascular occlusive device delivery catheters are just a sample of what is commonly used percutaneously to treat a wide variety of illnesses. The introduction of air into the blood stream can be quite serious, resulting in a stroke if it is allowed to migrate to the heart or brain (depriving the tissue of oxygenated blood).
FIG. 1 depicts the main components of an exemplary vasculature access device D, including a proximal hub H and a distal shaft F shown extending through an incision made in the patient's skin surface A and a puncture tract extending through the subcutaneous tissue and into a blood vessel BV of the patient's vasculature. With reference also to FIGS. 1A-1F, the proximal hub H includes a hemostasis port E that allows for access of a diagnostic, therapeutic or interventional instrument C to pass through the hub H and distal shaft F, respectively, into the blood vessel BV. A fluid-flush port G is also provided on the hub, as is well-known.
The present inventor has determined that introduction of air through the hemostasis valve E into the hub H for possible downstream migration to the vasculature may happen for a number of reasons. With reference to FIG. 1A, air can pass from the external environment through the hemostasis valve E, as indicated by arrows 20, while the instrument C is being passed through the hemostasis valve E, due to the valve design and a pressure differential i.e., when the pressure Pi within the interior of the hub H is less than the ambient pressure Ph. With reference to FIG. 1B, air can pass from the external environment through the hemostasis valve E, as indicated by arrow 21, when a pressure differential is created due to the movement of the instrument C, indicated by arrow 22, resulting from the instrument C acting as an “occlusive plug” 24 that creates a lower pressure Pi on the proximal side of the instrument within the hub H. With reference to FIG. 1C, air can pass from the external environment through the hemostasis valve E when the valve E is deformed or damaged by the passage of the instrument C, indicated by arrow 23, such as during multiple expansion/contraction cycles caused by interchanging a catheter and dilator. Air can also pass from the external environment through the hemostasis valve E while the instrument C is in place, due vigorous aspiration via the flush-port G, as indicated by arrows 20, 25 and 26, shown amongst the incoming air bubbles B in FIG. 1D. With reference to FIG. 1E, air can also pass from the external environment through the hemostasis valve E due to normal aspiration through the flush-port G, as indicated by arrows 27, when the valve E fails to recover to create a seal after the instrument C has been removed. With reference to FIG. 1F, it is also worth noting that air bubbles B drawn into the interior of the hub H, as indicated by arrows 28, may cling to the instrument C due to surface tension, indicated by reference number 29, and be drawn into the vasculature along with the instrument C.
The present inventor has also determined that it would be desirable to avoid this introduction of air into the interior hub H of the access device D, since this air can migrate through the distal shaft F and into the patient's vasculature.